


Just Us Three

by socksuckinglips



Series: Daddy's Little Boy [1]
Category: Supernatural
Genre: Anal Fingering, Anal Gaping, Anal Sex, Bestiality, Blow Jobs, Bottom Castiel, Butt Plugs, Come Swallowing, Extremely Underage, Felching, Knotting, M/M, Multi, Parent/Child Incest, Sex with Sentient Animals, Shapeshifting, Sibling Incest, Size Difference, Spitroasting, Top Dean Winchester, Top Sam, Uncle/Nephew Incest, Underage Castiel
Language: English
Status: Completed
Published: 2014-10-10
Updated: 2014-10-10
Packaged: 2018-02-20 13:51:47
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 3,829
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2431199
Author URL: https://archiveofourown.org/users/socksuckinglips/pseuds/socksuckinglips
Summary: <blockquote class="userstuff">
              <p>Dean has a night at home with his son and his brother. Cas has a surprise for him.</p>
            </blockquote>





	Just Us Three

**Author's Note:**

> Inaugural sock account fic!
> 
> Castiel is Dean's 10 year old son. Sam is a dog shapeshifter. This is dirty bad wrong in all sorts of ways, so please proceed with caution.

Dean sets his keys down on the small table in his entryway and smiles. It's not often that he gets home from work early, and he's looking forward to a night with his boys.

 

He can hear the opening bars of “Batman: the Brave and the Bold” filtering in from the living room. Sam only lets Cas watch cartoons after he's finished his homework. Dean shrugs his coat off and hangs it up, feeling relieved that Cas won't have to worry about any more schoolwork tonight.

 

Dean has much better plans.

 

He kicks his shoes off and pads into the living room as quietly as possible. He always tries to catch these moments, seeing his brother and his sweet little son relaxing together. As Dean peeks his head around the doorway, he arches an eyebrow and licks his lips. Looks like Sam and Cas have been doing a little more than relaxing.

 

It's been chilly outside but Sam always keeps the heat cranked up. So it's not surprising to see Sam sitting in nothing but his boxer shorts on the big chair in front of the TV. Cas is wearing his favorite Batman t-shirt and a pair of plain blue briefs. Even if the way he's squirming didn't give them away, the hand Cas has down his shorts sure does. Dean indulges himself for a moment, watching the way Cas squirms on Sam's lap as he smiles at the TV. Dean cups himself over his pants, feeling his cock thicken just thinking about Cas having some playtime with his Uncle Sam. It made Dean's workdays seem so much longer, knowing that Sam got to spend all afternoon with his boy.

 

Cas laughs at something and looks up at Sam. Dean gives himself another furtive rub as he watches Cas smile. He's such a pretty boy, all big blue eyes and pretty black curls. His legs drape over either side of Sam's, slender and pale just like the rest of him. At 10 he's a little old for cartoons, but Dean encourages as much childish behavior as possible. He doesn't want Cas growing up too fast, there'll be plenty of time for that later.

 

“You two look like you've been having a good time without me.” Dean steps into the living room and kneels down as Cas jumps off Sam's lap.

 

“Daddy!” Cas shrieks, barreling towards him and wrapping his legs around Dean's waist. Cas is always so happy to see him and it makes Dean's heart twitch. “Oh I missed you, Daddy.”

 

“I missed you too, baby.” Dean ruffles his hair and leans down for a kiss, sighing as his son's sweet little tongue curls eagerly into his mouth. Cas knows to only give grown-up kisses when he's alone with Dean or Sam.

 

Dean stands up, taking Cas with him easily. He's still so light in Dean's arms.

 

“Missed you too, furball.” Dean leans in to give Sam a kiss while Cas squirms in his arms.

 

“Cas has something to show you, Dean, I don't think we should keep him waiting.” Sam smiles indulgently and looks over at Cas, who's wriggled out of Dean's arms to stand in front of them. Dean sits down and crosses his legs, holding his hands out in front of him.

 

“Well alright, then.” Dean laughs. Cas looks like he's about to burst with excitement, stepping back and forth from one foot to the next.

 

“Cas had some very specific ideas about how he wanted to spend tonight, and he asked me for some help,” Sam explains. “Wanna show him, Cas?”

 

Cas nods his head and bites his lip, holding back a huge grin as he slowly tugs his briefs down. Dean certainly didn't encourage Cas to be a tease, but it did seem to come naturally to him. He lets his little shorts pool around his ankles, resting his hands on his waist.

 

Dean's mouth waters at the sight of Cas's sweet little cock. Cas is still smooth and hairless down there, with tight little nuts that nestle up right under his prick. Dean had been thinking about putting his son's little dick in his mouth all day. But Cas clearly has other things in mind.

 

“Uncle Sam helped me get ready,” Cas says as he gets down on his knees, smiling at his uncle before turning around. Dean spares a quick glance for Sam, who just licks his lips and gives Dean a suggestive look. Dean turns back and immediately groans at the sight in front of him.

 

There, nestled in between Cas's little buttcheeks, is one of the buttplugs they'd bought for him last month. It's the biggest one they'd gotten, not as big as Sam or Dean's cocks but still a challenge for Cas' tight little hole.

 

Dean had given in a few months ago. He knew he was doomed when he rimmed Cas for the first time, burying his tongue in that tight ring of muscle and hearing all the noises Cas made. He'd already taught Cas how to take a cock in his mouth, and his boy was a good student.

 

And, as Dean and Sam had learned a few weeks after they'd started eating his little ass, he was a total cockslut. It had started with fingers, Dean first, then Sam, then both of them at once. Cas had taken to it like a fish to water, begging for more while they'd fingered him open and moaning out the dry little twitches that passed for his orgasm.

 

Dean would never forget the first time, as he'd watched Cas's tiny, pink little hole open up for his cock. He'd used enough lube to drown him, and it had taken all night, but the sight of the wide-eyed look of glee on Cas's face as he sank down onto his Daddy's cock was the best thing Dean had ever seen. Sam was even thicker than Dean, and Cas had taken him like a little champ.

 

But just like Cas, he was always pushing for more. It was hardly a secret that he had them both wrapped around his little finger. Like they could say no when he asked for things to play with while Dean was at work.

 

“Holy ...” Dean trails off, reaching out to run his finger over the smooth silicone. “Sammy helped you get your toy inside, huh?” Dean swallows thickly, giving Sam a heated look. “How did he help?” Dean grabs the base of the plug and twists, feeling his dick twitch at the little squeal Cas lets out.

 

“He, oh, Daddy!” Cas looks back at him as Dean starts to work the plug out. “He used his fingers in my, oh, in my boyhole, and his, oh Daddy, and his tongue, his Sammy tongue and oh, oh _Daddy_!” Cas whines as the plug slips free. Dean quickly replaces it with two of his fingers, groaning as they sink into the slick pink of Cas's boyhole. That had seemed like the best name for it. Dean wasn't about to call it “heaven,” even if that's what it felt like, tight and hot around his fingers.

 

“Cas was so good.” Sam slides off the chair and comes to sit next to Dean. The head of his cock peeks out through the slit of his boxers, purpled and pearled at the tip. Not like Dean could blame him.

 

“He was really patient, weren't you, Cas?” Sam reaches his hand under Dean, stroking this thumb fondly over the tight little seam of Cas's balls. “Let me get him nice and open, with lots of sticky stuff.”

 

“Even though the sticky stuff was all cold.” Cas pouts over his shoulder. Dean didn't want Cas to know words like “lube” or “blowjob” yet, so they had their own language for the things they did in private.

 

“I know it's cold, baby, but you need it to be safe, remember?” Dean looks down at the shine on his fingers as he draws them out. Sam took good care of Cas and always used enough.

 

“I'm proud of you, Cas.” Dean sinks a finger back in, pulling Sam's wrist up until he gets the message and sinks one of his own in next to Dean's. “And I know Uncle Sam's proud, too.” Cas smiles and closes his eyes as they take turns fingering his little hole.

 

“So you had some plans for tonight, huh?” Dean arches an eyebrow at Sam, who just smiles and palms his dick with his free hand. These are definitely going to be good plans. “What do you want, baby? Come sit on Daddy's lap and tell me.”

 

Sam wipes his finger on Dean's shirt and smirks at the dirty look Dean gives him before shrugging and doing the same. Cas crawls over and wriggles onto Dean's lap, wrapping his legs around Dean's waist and facing him. He looks back and forth between Dean and Sam, pulling Sam's hand in and hugging it to his chest.

 

“I want Sammy to put his come in my boyhole,” Cas says breathlessly, squirming like an eel as he looks at Dean. “And I want Daddy to put it in my mouth.” Cas blinks and tilts his head, giving Dean that looks he gives when he's not sure Dean's smart enough to follow him. “Together, you know, like last time?”

 

Dean definitely remembered last time. Seeing Cas stuffed with cock at both ends wasn't something he was liable to forget, even if Cas seemed to think Dean was a scatterbrain who never remembered anything.

 

“Yeah, I remember, baby.” Dean pulls Cas in closer, groaning as he feels his son's weight press down on his cock. “That sounds so good, Cas, you know you look so good with Uncle Sam's pee-pee inside you.” Dean couldn't stand the thought of Cas saying “cock” or “dick”, although Dean slipped up sometimes in the heat of the moment.

 

“No, Daddy.” Cas shakes his head and rolls his eyes. “I want _Sammy_.”

 

Dean's throat goes dry as his mouth hangs open. He looks over at Sam and swallows a few times, absently thinking that he deserves an award for not jizzing himself right there.

 

“I want him to put his doggy come in me.”

 

Dean's hand flies down to stave himself off, knowing that only the fact that he'd jerked off in the bathroom at work thinking about Cas's sweet mouth around his dick was keeping him from coming right then.

 

Having a shape-shifter for a brother certainly had its benefits, as Dean had learned at an early age. At a slightly older age, he'd really learned those benefits. Dean had spent most of high school weekends picking up girls with Sam, learning which ones were likely to bolt at the first glimpse of Sam turning into a dog and which ones were, well, a little more liberal.

 

Dean had started calling dog-Sam “Sammy” mostly because for once, Sam couldn't talk back to him and tell him to go fuck himself. The habit had stuck and Cas had picked it up. He loved playing with Sammy, whether it was wrestling around with him or letting Sammy's long tongue lick his little hole and his stiff little dick until he came. More recently Sam had gotten it in his head to lick around Cas's stretched little hole while Dean fucked him. They both liked that.

 

Cas had seen Sam's doggy dick plenty of times. If things got stressful, Sam would spend an entire day or two in his dog form. Many nights in their house passed quietly, with Cas mumbling around a mouthful of Dean's dick while Sam sat in the corner and licked himself. Dean was pretty sure he did it just to rub it in – like any sane man wouldn't lick his own ass if he could.

 

Cas had the natural curiosity of any smart kid, and he'd been fascinated by the shape of it when Sammy got hard. Sam liked getting a handjob better when he was a dog, so Dean had shown Cas what happened when Sammy came, how his knot swelled up and how he came for a longer time.

 

But Cas had never seen Sammy actually fuck someone before. As much as Dean missed watching Sam hump some pretty coed, they'd stopped bringing people home after Cas arrived. And Dean had let Sammy fuck him once and once only, deciding he was a better voyeur than a bottom.

 

Dean looks back and forth between his brother and his son, wondering if anyone on earth is as happy as Dean is.

 

“Oh, Cas.” Dean smiles and kisses him, running his hands up Cas's back. He kisses Sam, too, murmuring _love you_ as Sam laughs.

 

“It was his idea, I swear.” Sam holds his hands up, all innocence as Cas giggles.

 

“It was, Daddy. Sammy was licking me and I saw his pee-pee and I couldn't stop thinking about it.”

 

Cas isn't the only one who can't stop thinking about it. Dean shifts him off his lap and looks down at his erection straining the front of his slacks.

 

“I think that's a great idea, Cas.” Dean and Sam get up on their knees at the same time. Dean strips out of his clothes as fast as he can. His dick bobs up in front of him, thick and hard with a clear stream of precome leaking from the tip.

 

“See how hard you made Daddy, Cas?” Dean strokes himself and squeezes out another bead of precome. “Such a good boy for me, baby.”

 

Cas grins at him and turns around, settling on all fours with his butt up in the air. The rim of his hole is shiny with lube, but Dean still grabs the bottle off the coffee table.

 

“Don't forget to slick me up.” Sam whispers in his ear, earning a pointed look from Dean. Like he'd ever forget. Sam winks and tugs his boxers off, settling on all fours next to Cas.

 

Dean's never really been able to explain it. One minute Sam's a dude, the next he's a dog. A huge, very excited dog. If Dean had to pick a breed he'd go with German Shepherd, although he'd never met one as big as Sammy.

 

“Sammy!” Cas laughs as Sammy licks his face. Dean rolls his eyes and squeezes out some lube onto his fingers.

 

“Ergh, cold!” Cas mewls as Dean works his fingers in. He scissors them open and squirts some right out of the bottle into Cas's clenching hole. He's about as open as he's gonna get.

 

Sammy clambers next to him, cock out and ready to go. Dean gives him an affectionate scratch between the ears before squirting another dollop of lube onto his palm. He slicks it onto Sammy's dick slowly, stroking him a few times before Sammy gives him a petulant whine.

 

“Bitch,” Dean whispers softly, hoping Cas doesn't hear him. Sammy just grunts and does the dog version of flipping his hair.

 

“You ready, baby?” Dean sinks three fingers into Cas's hole. “Sammy's really excited.” Sam barks once, making Cas laugh.

 

“Yes, Daddy, come on,” Cas whines impatiently, circling his hips back and forth. Normally Dean would chide him for that tone, but he figures he can let it slide for now.

 

“Alright, baby, here we go.” Dean keeps his hand wrapped around Sammy's slick cock as he lines the tapered head up with Cas's hole. Sammy's cock is red and soft, like the girl parts Dean used to watch him sink into just like he's sinking into Cas now.

 

Cas is so much better.

 

“There it is, good boy,” Dean murmurs, pulling his hand back as Sam buries himself to the fold of his sheath. His paws cross around Cas's slender waist, getting a good grip while Cas stretches around him. Once Dean's sure he's set up, he hustles up to Cas's front.

 

“How's that feel, baby?” Dean traces down the soft curve of Cas' cheek, petting him as Cas's eyes go wide.

 

“Oh, Daddy, it's good, it's so big but it's good, hngh...” Cas trails off as Sam curves his back, getting ready to thrust into Cas. “I'm ready, Sammy, do it.”

 

Dean squeezes a tight hand around the base of his cock as Sam pistons his hips forward. Cas makes the most delicious sounds when he's getting fucked, all high-pitched squeals and moans. His little body shakes each time Sammy thrusts into him. Dean knows Sam must feel heavy but Cas doesn't complain once, just squares his little shoulders and takes it.

 

“Daddy, unh, want you, Daddy,” Cas mumbles, his eyes getting a little unfocused as Sammy fucks him faster. Dean can hear the slap of Sammy's body into Cas's hole, wet and nasty and so much better with Cas's sweet little face looking up at him and begging for more.

 

“You're gonna make Daddy come too fast, baby, you know how good you look with that big doggy dick in your little boyhole?” Dean gives himself a testing stroke before clamping his hand back quickly. He doesn't want to blow his load yet and he is way too close.

 

“You look so good, Cas, take it like such a good boy. Sammy can tell you later but I bet your boyhole feels really good to him.” Sammy growls what Dean assumes is agreement, although as Dean watches Sam's pace start to get more erratic he wonders if it's a warning.

 

“Cas, how do you feel?” Dean leans down so he can see Cas's face better.

 

“It's, oh, it's big, Daddy, it's really, really big, unh...” Sam growls again as he starts to take longer thrusts.

 

“Thought so.” Dean smiles and kisses Cas. “That's his knot, baby, it's getting big for you.” Cas looks dazed as he grits his teeth. “Sammy's gonna come in your boyhole, Cas, just try to relax.” Dean strokes his hand down Cas's back, feeling Cas go tense under his hands as he strains to take the knot.

 

“You can do it, baby, that's it.” Dean wipes the sweat from his forehead and releases his hold on his dick. “Let him get that knot inside you, good boy.” A fat pulse of precome leaks out of Dean's cock as he brings his other hand to pet Cas's back. “You're gonna make him come, Cas, aren't you? Gonna let Sammy put his puppies inside you?”

 

Cas throws his head back and lets out a long, high noise as Sam goes still. Dean strokes both hands down Cas's sides, shushing him as Cas adjusts to the fat knot inside him.

 

“You feel that, Cas? He's all tied up inside you, knotted good in your little boyhole.” Dean runs his hand through Cas's hair and kisses him.

 

“It's hot,” Cas says weakly, panting for breath. His face is flushed as he smiles up at Dean. He looks so proud of himself. Dean thinks about that big knot swelling up inside his little boy and feels his cock twitch. He rarely thinks it, but right now he wouldn't mind if Cas were a girl. He'd always liked double-teaming the girls they brought home, feeling Sammy's knot rub against his dick as he came inside her. But he wouldn't trade Cas for anything.

 

“You made him come, baby.” Dean takes his cock in his hand and strokes it, bringing the head to Cas's lips. “Good boy, you want your reward? You want Daddy to put his come in your mouth?” Cas nods and opens his lips so readily Dean barely makes it inside before he's spilling out. Cas always does his best to swallow it all, but he's too fucked out from Sammy's knot to do much more than let it dribble down his chin. Dean doesn't mind. He just cradles Cas's sweet, messy little face in his lap as Sammy huffs and rides out the rest of his orgasm.

 

“I'm tired, Daddy,” Cas mumbles a while later, shifting around on his elbows. Dean knows Sammy will stay inside him as long as he can.

 

He reaches over and taps Sammy on the nose. “You done, furball?” Sammy manages to pull a bitchface and roll his eyes, which Dean is 99% sure dogs are not supposed to be able to do. But after a few seconds he lets out a long sigh and shifts back to human.

 

Cas starts in surprise as Sam changes back. He hauls Cas up with him, hands still clasped around his waist and his cock still buried inside him. Sam's grinning like a maniac as he kisses Cas wherever he can reach.

 

“Oh my God, Cas, that was amazing.” Sam kisses him over and over as Cas giggles sleepily. “You are so good, baby, you know that?”

 

“Of course he knows.” Dean gives Cas a kiss of his own before sliding next to Sam. “I have got to see this,” he mumbles as he watches Sam's spent dick slip out of Cas's hole.

 

A fat line of come drips out after it, running down Cas's skinny leg. Dean barely notices it, not with the filthy, gorgeous gape of Cas's hole. It's puffed and stretched, shiny red around the rim and slick with come and lube. Cas coughs lightly, pushing out another slick trail of come that trails down his little balls.

 

“Holy-” Dean cuts Sam off before he can curse, not that he isn't thinking the same thing. _Holy fucking shit fucking christ fuck_ runs through Dean's head like a parade. “Yeah, I know.” Dean presses a kiss to Sam's shoulder.

 

“Dean, I have to...” Sam leans down, his mouth open and his tongue snaking out before he's even halfway to Cas's hole.

 

“I know, I know, hang on.” Dean shoulders him aside before gently rolling Cas onto his back. Sam is nothing if not predictable at times.

 

“There we go, baby, let's lay you down.” Dean grabs blindly for a pillow off the couch and cushions Cas's head on it. “Know what Sam wants to do, Cas?” Dean lays down next to him, trailing his hand up the flat expanse of Cas's chest.

 

“What?” Cas asks sleepily, yawning as he stretches his arms over his head. Cas always nods off after getting fucked. He'll be up in a few hours demanding a snack and crawling onto the nearest lap for a snuggle.

 

“He's gonna lick all his come out of your boyhole.” Dean kisses Cas on the cheek, watching his son smile.

 

“OK, Uncle Sam.” Cas yawns again as Sam settles between his legs, pushing them up to his chest and closing his mouth over Cas's hole with a wet slurp. Cas moans and wriggles down onto Sam's face, turning to look at Dean and blink his eyes like a perfect angel.

 

“Daddy, when Uncle Sam is done, can I have cookies?”

 

Dean laughs and tucks Cas under his arm, kissing him on the forehead as Sam chuckles.

 

“Yes, baby. You can have anything you want.”

 

 


End file.
